Mike Nudelman/Business Insider
As real-estate mogul Donald Trump rocketed up the polls in the GOP presidential primary, many observers have been left scratching their heads.

After all, his baffled critics argue, Trump is merely a celebrity candidate with a gigantic amount of name recognition being further lifted by the media maelstrom that follows his every tweet, statement, and speech.

Rival candidate Sen. Rand Paul (R-Kentucky) this week attributed Trump's rise to a brief "loss of sanity" in the race.

"I think this is a temporary sort of loss of sanity. But we're going to come back our senses and look for somebody serious to lead the country at some point," Paul said in a Thursday CNN interview.

It does appear, however, that Trump has a real base of support — at least for now.

"He's not going away," Steve Duprey, a Republican National Committee member, told Reuters when the wire service published yet another poll showing Trump ahead. "There are people who think his candidacy is a flash in the pan or a flash in the moment, but I think that underestimates his appeal."

Earlier this week, Bloomberg Politics managing editor John Heilemann sat down with a focus group of Trump fans in New Hampshire to feel out why they liked the real-estate developer and television personality as a presidential candidate. Though some of the participants support Trump's GOP rivals, many of them still gushed over his candidacy and praised his controversial rhetoric against illegal immigration.

"He says it like it is. He speaks the truth," said one woman in the focus group. "When he talks about especially immigration control and the border, he doesn't care what people think. He tells the truth, what we need to do."

Another participant said Trump's blunt approach contrasts sharply with how most politicians speak and address the issues of the day.

"The way I see it: The political rhetoric — most of the politicians — talk in let's say pastel colors. They talk for two hours and you go away saying, 'What did they say of substance?' Probably nothing. But they haven't offended anybody and tried to make everybody their friend. Well, if they're pastel, Donald Trump is vivid colors, because he says things the way they are," he said.

A third person compared Trump to former President Ronald Reagan, a hero for many Republicans.

"I like his roughness," she said. "A little Reaganesque comes to mind. Just tough. We need someone tough."

Yet another participant asked what a Trump presidency would look like, responded: "classy."

Watch below:

Trump's base

"In Trump's case, he appears to be cornering the market on white voters, the backbone of the current Republican Party, the poll shows," he wrote. "Republicans need as many white votes as possible to offset demographic shifts in the United States that have handed Democrats an electoral advantage in the last two presidential elections."

A Quinnipiac University poll of the Republican primary this week also found that Trump performed better with men than woman. Trump got 24% of the male vote and 15% of the female vote — a noticeable gap, though he still had more support between both sexes than any of his GOP rivals.

Trump performed more or less evenly across the board when it came to the ideological spectrum of voters. The Quinnipiac survey found that Trump had the plurality among self-identified tea party (23%), evangelical (20%), very conservative (20%), somewhat conservative (24%), and moderate/liberal (17%) Republican voters.

Donald Trump.
REUTERS/David Moir

Warning signs

However, Trump's numbers do contain warning signs. Notably, Trump may be achieving his relatively low plurality of the vote thanks to the crowded Republican field, which features a number of top-tier candidates with millions of dollars behind them and their super PACs.

Public Policy Polling, a Democratic-leaning firm, was one of several pollsters to recently note that Trump is among the most unpopular candidates overall and could suffer in the general election if he is the nominee. And as the Republican field narrows, the non-Trump vote could theoretically consolidate behind fewer and fewer candidates.

"Donald Trump continues to lead the Republican primary field," Dean Debnam, president of Public Policy Polling, said in a statement last week. "But there are signs his decline may be starting with GOP voters — and when it comes to the general election his numbers are an unmitigated disaster."

"According to the latest polling, Trump commands the support of roughly 20 percent of Republican voters nationally," he wrote. "That may prove to be his ceiling; we shall see. But judging from our focus group, anyone who believes Trump is merely this cycle's incarnation of Michele Bachmann or Herman Cain — a shooting star destined to fall to earth as rapidly as he rocketed skyward — is out to lunch."

Heilemann added: "The support for The Donald on display among the supporters I met was striking for its depth and intensity."